Method of release and product flow management for a manufacturing facility

ABSTRACT

A method and computer program product for scheduling product lots through operations of a manufacturing line. The method including: selecting a sequential subset of a set of sequential operations required to manufacture the lots; partitioning the product lots into designated lots and non-designated lots; and generating a release schedule for each of the non-designated lots into one or more operations of the sequential subset of the set of sequential operations; generating a release schedule for each of the designated lots into each operation of the sequential subset of the set of sequential operations such that for each designated lot a total amount of time measured from completion of a first operation of the sequential subset of the set of sequential operations through start of a last operation of the sequential subset of the set of sequential operations does not exceed a target amount of time for the designated lots.

FIELD OF THE INVENTION

The present invention relates to the field of manufacturing facilitycontrol such as used in a semiconductor manufacturing facility; morespecifically, it relates to a method and system for release to andproduct flow management of product in a manufacturing facility.

BACKGROUND OF THE INVENTION

Manufacturers, such as but not limited to semiconductor manufacturers,continually strive to increase yield and reduce cycle time in order tooperate at the lowest possible cost. Conventional product release andproduct flow management methods address only logistic concerns such ascycle time and delivery schedule control. The problem of yieldenhancement has been left to either improvements in tooling orestablishment of simple process window/rework time windows. The abilityto influence yield has otherwise been left un-addressed by productrelease and product flow management methods.

Therefore, there is a need for a method of release and product flowmanagement for a manufacturing facility that allows for improved yieldas well as cycle time and delivery schedule control.

SUMMARY OF THE INVENTION

A first aspect of the present invention is a method for scheduling lotsof product through operations in a manufacturing line, comprising:selecting a sequential subset of a set of sequential operations requiredto manufacture the lots; partitioning the lots of product intodesignated lots and non-designated lots; and generating a releaseschedule for each of the non-designated lots into one or more operationsof the sequential subset of the set of sequential operations; generatinga release schedule for each of the designated lots into each operationof the sequential subset of the set of sequential operations such thatfor each designated lot a total amount of time measured from completionof a first operation of the sequential subset of the set of sequentialoperations through start of a last operation of the sequential subset ofthe set of sequential operations does not exceed a target amount of timefor the designated lots.

A second aspect of the present invention is a computer program product,comprising a computer usable medium having a computer readable programcode embodied therein, the computer readable program code comprising analgorithm adapted to implement a method for scheduling lots of productthrough operations in a manufacturing line, the method comprising thesteps of: selecting a sequential subset of a set of sequentialoperations required to manufacture the lots; partitioning the lots ofproduct into designated lots and non-designated lots; generating arelease schedule for each of the non-designated lots into one or moreoperations of the sequential subset of the set of sequential operations;and generating a release schedule for each of the designated lots intoeach operation of the sequential subset of the set of sequentialoperations such that for each designated lot a total amount of timemeasured from completion of a first operation of the sequential subsetof the set of sequential operations through start of a last operation ofthe sequential subset of the set of sequential operations does notexceed a target amount of time for the designated lots.

A third aspect of the present invention is a system for scheduling lotsof product through operations in a manufacturing line, comprising: azone of control creation module for initializing a zone of controldatabase for a zone of control of a manufacturing line, the zone ofcontrol comprising a sequential subset of a set of sequential operationsrequired to manufacture the lots, the lots of product partitioned intodesignated and non-designated lots; a zone of control release module forplanning a release schedule for the designated lots of the lots intoeach operation of the zone of control to meet a total amount of timetarget, the total amount of time target measured from completion of afirst operation of the zone of control through start of a last operationof zone of control; a zone of control monitor module for updating therelease schedule of the designated lots and release schedules of thenon-designated lots into each operation of the zone of control; and awhat next module for selecting a next lot from the designated and thenon-designated lots to release into each operation of the zone ofcontrol.

BRIEF DESCRIPTION OF DRAWINGS

The features of the invention are set forth in the appended claims. Theinvention itself, however, will be best understood by reference to thefollowing detailed description of an illustrative embodiment when readin conjunction with the accompanying drawings, wherein:

FIG. 1 a diagram of a portion of a manufacturing line according to thepresent invention;

FIG. 2 is a system diagram of a zone of control system according to thepresent invention;

FIGS. 3A through 3E illustrate the file structure of a the zone ofcontrol system of FIG. 2;

FIG. 4 is a flowchart of a method of release and product flow managementaccording to the present invention;

FIG. 5 is a flowchart of step 215 of FIG. 4;

FIG. 6 is a flowchart of steps 220 and 225 of FIG. 4;

FIG. 7 is a flowchart of step 305 of FIG. 6;

FIG. 8 is a flowchart of step 315 of FIG. 7 and step 445 of FIG. 11;

FIG. 9 is a flowchart of step 230 of FIG. 4;

FIG. 10 is a flowchart of steps 235 and 240 of FIG. 4;

FIG. 11 is a flowchart of step 425 of FIG. 10;

FIG. 12 is a flowchart of steps 435 of FIG. 10 and 480 of FIG. 11;

FIG. 13 is a flowchart of step 245 of FIG. 4; and

FIG. 14 is a schematic block diagram of a general-purpose computer forpracticing the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In a semiconductor environment it was discovered that yields on certainproducts increase if several distinct but sequential operations wereperformed within a given amount of time. This sequence of operations iscalled a yield management zone of control (ZOC), hereinafter ZOC. Thetools are designated ZOC tools and a ZOC product to be yield managed isrun in ZOC lots of one or more pieces through the ZOC tools in sequence.This effect is different from the time window effect affecting twosequential process steps where the first step can be repeated if a timelimit expires. Though applicable to other conditions, the presentinvention was developed to address the condition of sequential multipleoperations, each operation requiring a different fabrication tool andwhere there may be multiple operations within a tool, where there may bemultiple tools for any particular operation, where rework may not bepossible and/or where non-ZOC lots (those lots whose yields do notchange significantly as a function of their cycle time) may share one ormore of the ZOC tools.

For the purposes of the present invention, a lot may comprise a singlepiece (for example, a single wafer in a semiconductor manufacturingline) or a group of two or more pieces (for example, two or more wafersin a wafer lot in a semiconductor manufacturing line) not withstandingthe fact, that in some tools pieces of the same lot may be processedtogether and in some tools pieces of the same lot may be processedsequentially (e. g. single wafer vs. batch tools).

FIG. 1 is a diagram of a portion of a manufacturing line according tothe present invention. In FIG. 1 a ZOC 100 contains multiple ZOCoperations (operations are also known as manufacturing activities) froma first ZOC operation 105A, a second ZOC operation 105B, a third ZOCoperation 105C through a last ZOC operation 105N. ZOC operation 105A,105B, 105C through 105N operations may be expresses as ZOC operation 1,ZOC operation 2, ZOC operation 3 . . . through ZOC operation N. Forexemplary purposes, ZOC operation 105A includes process tools 110A and110B, ZOC operation 105B includes process tools 115A, 115B and 11 SC,ZOC control 105C includes process tools 120A, 120B and 120C, and ZOCoperation 105N includes process tools 125A and 125B. Process tools 110Aand 110B can both perform the same process, so a ZOC lot can be run oneither of ZOC tools 110A or 110B in ZOC operation 105A. Process tools115A, 115B and 115C can all perform the same process, so a ZOC lot canbe run on any of ZOC tools 115A, 115B or 115C in ZOC operation 105B.Process tools 120A, 120B and 120C can all perform the same process (orprocesses, i. e. are cluster tools), so a ZOC lot can be run on any ofZOC tools 120A, 120B or 120C in ZOC 105C. Process tools 125A and 125Bcan both perform the same process, so a ZOC lot can be run either of ZOCtools 125A or 125B in ZOC 105N. While specific numbers of process toolsare illustrated in FIG. 1 for each ZOC operation, a given ZOC operationmay include any number of ZOC tools from one up. Also, while all the ZOCoperations are illustrated in proximity to one another, ZOC tools may beplaced throughout a manufacturing line.

All ZOC tools 110A, 110B, 115A, 115B, 11SC, 120A, 120B, 120C, 125A and125C are illustrated as having load/unload (L/UL) stations 130 (whichmay include storage buffers) which are connected to an automateddelivery system 135 and computer control/monitor stations 140 providinga link between ZOC tools and a manufacturing execution system (MES) 145.The general function of an MES function is to schedule, release andtrack product lots to and through the tools of a manufacturing line byissuing specific execution instructions (lot movement instructions) to afloor control system. The function of MES 145 in relation to ZOC 100 isto issue specific lot movement and tool assignment instructions to thefloor control system if not completely generated by then at leastlogically based on input from WNMs 185A, 185B through 185N (see FIG. 2.

ZOC tools may be manual tools and not connected to delivery system 135(e. g. human operators may move ZOC lots from ZOC tool to ZOC tool). ZOCtools need not be directly linked connected to MES 145 (e.g. humanoperators may receive and record ZOC lot/tool information from MESterminals distributed through a manufacturing line.

FIG. 2 is a system diagram of a zone of control system according to thepresent invention. In FIG. 2, a ZOC system 150 includes a ZOC creationmodule (ZOC CM) 155 and an associated ZOC CM file 160, a ZOC game planrelease module (ZOC GPRM) 165 and an associated ZOC GPRM file 170, a ZOCgame plan monitor module (ZOC GPMM) 175 and an associated ZOC GPMM file180, and a set of what next modules (WNM) 185A, 185B through 185N (forcorresponding ZOC operations, 1, 2 through N) and a corresponding WNMfile(190). ZOC system 150 further includes a ZOC lot tracking file 195.ZOC CM 155, ZOC GPRM 165 and ZOC GPMM 175 all generate output that isstored in and/or can be retrieved from ZOC lot tracking file 195. Itshould be noted that the file system comprising ZOC CM file 160, ZOCGPRM file 170, ZOC GPMM file 180, WNM file 190 and ZOC lot tracking file195 may be replaced by other file systems or data storage systems asknown in the art. ZOC CM 155 can issue instructions and/or send data toZOC GPRM 165, ZOC GPRM 165 can issues instructions and/or send data toZOC WNM 185A (first ZOC operation) and ZOC GPMM 175 can issuesinstructions and/or send data to ZOC WNMs 185B through 185N. MES 145(see FIG. 1) and associated MES file 200 are not part of ZOC system 150but MES 145 can issue instructions to and/or send data to ZOC CM 155,ZOC GPRM 165 and ZOC GPRM 175 and can issue instructions to and/or senddata to and/or receive data from WNM 185A, 185B through 185N. ZOC GPMM175 can issue a critical action report 205 and an alert report 210 asrequired.

Briefly, ZOC CM 155 creates a file that defines a ZOC that MES 145 mayutilize to schedule and route ZOC and non-ZOC lots through ZOC system150. ZOC GPRM 165 generates a release schedule/tool assignment to thefirst of ZOC operation 105A of ZOC 100 (see FIG. 1) that will meet theyield window time restraint of the ZOC. ZOC GPMM 175 generates andupdates ZOC lot priorities for the second through nth last operation ofrespective ZOC operations 105B, 105C through 105N of ZOC 100 (seeFIG. 1) that will meet the yield window time restraint of the ZOC. WNM185A, 185B through 185N identify ZOC and non-ZOC lots for the tools oftheir respective ZOC operations, prioritize the ZOC and non-ZOC lotsaccording to pre-defined rules, and assign the ZOC and non-ZOC lotsaccording to predefined algorithms. WNM 185A, 185B through 185N operatein real time.

ZOC system 150 generates, track and modifies ZOC lot schedules in theZOC so ZOC lots start and finish through ZOC operations within a targettime window that prevents delay related yield degradation, taking intoaccount that there may be several ZOC lots and several non-ZOC lots thatwill use the same tools and schedules for all lots must be met.

FIGS. 3A through 3E illustrate the file structure of the zone of controlsystem of FIG. 2. In FIG. 3A, ZOC CM file 160 includes a ZOC operationsfile, a ZOC tool file, a ZOC lot ID file, a ZOC allowable delay timefile, a ZOC knowledge base file, a ZOC required cycle time file and anon-ZOC lot ID file. The ZOC operations file lists the manufacturingoperations for the ZOC. The ZOC tool file lists tools that perform theoperations of the ZOC. The ZOC lot ID file list the lots that are to beprocessed as part of the ZOC. The ZOC allowable delay time file givesmaximum delay times between operations in the ZOC. The ZOC knowledgebase file includes specific processing related schedule information, forexample, for how many pieces could mask cleaning be delayed if a ZOCrequired a masking operation using a mask scheduled for cleaning. TheZOC required cycle time file gives the maximum delay between the firstand last operation of the ZOC. The non-ZOC lot ID file lists non-ZOClots that will be run on the ZOC tools.

In FIG. 3B, ZOC GPRM file 180 includes a ZOC lot release file whichlists the ZOC earliest lot release date/time into the first operation ofthe ZOC. GPRM file 170 contains data pertinent to the first ZOCoperation.

In FIG. 3C, ZOC GPMM file 170 include a ZOC lot priority file, a ZOC lotalert file, a ZOC lot critical list file, a recover options file, and anon-ZOC lot priority file. GPMM file 170 contains data pertinent to thesecond through last ZOC operations. The ZOC lot priority file lists thecurrent relative priorities of ZOC lots. The ZOC lot alert file listsZOC lots that have scheduling problems jeopardizing the ZOC time window.The ZOC lot critical list file lists ZOC lots which require recoveryactions be taken in order to meet the ZOC time window. The recoveroptions file contains potential actions that may be selected to recovera ZOC lot on the critical list to the ZOC time window. The non-ZOC lotpriority file lists the current relative priorities of non-ZOC lots.Several ZOC lots and non-ZOC lots may share the same priority or ZOClots and non-ZOC lots may be ranked in priority in a single listdepending upon the type of MES used.

In FIG. 3D, WNM file 190 includes a dispatch list file which lists whichof the ZOC and non-ZOC lots each ZOC operation are to be processed nextand on which ZOC tool.

In FIG. 3E, MES file 200 includes a routing file, a tool file, a work inprogress (WIP) file and an acceptable delay file. The routing file listsall the operations each lot must be processed through in the entiremanufacturing line. The tool file lists the tools and status availablefor each operation in the manufacturing line. The WIP file lists thepresent status of all lots in the manufacturing line in two categories,those lots available to run on each tool in each operation, and thoselots either assigned to or already in each tool (or tool buffer) in eachoperation. The acceptable delay file lists the time windows that can notbe exceeded between two sequential operations (this is not the ZOC timewindow which is for the entire set of ZOC operations).

FIG. 4 is a flowchart of a method of release and product flow managementaccording to the present invention. In step 215, operations 1 through N(or last) are selected for inclusion in a ZOC of control and a ZOCcontrol is created. Step 215 is illustrated in FIG. 5 and described infurther detail infra. In step 220 all ZOC lots available for processingthrough the first operation of the ZOC are identified and in step 225,an earliest release date/time into the first ZOC operation is generatedfor all ZOC lots available for starting in the first ZOC operation.Potential release date/times into subsequent operations of the ZOC aregenerated by the process used to generate the release date/time into thefirst ZOC operation. Steps 220 and 225 are illustrated in FIG. 6 anddescribed in further detail infra. In step 230, the specific ZOC andnon-ZOC lots to dispatch next into the ZOC tools of the first ZOCoperation are selected and dispatched though a MES.

In step 235 all ZOC lots available for processing through each operationof the second through last operations of the ZOC are identified and instep 240, release date/times to the second through last ZOC operationsis generated for all ZOC lots available for starting in each of thesecond through last ZOC operations. Steps 235 and 240 are illustrated inFIG. 10 and described in further detail infra. In step 245, the specificZOC and non-ZOC lots to dispatch next into each ZOC tool of each of thesecond through last ZOC operation are selected and dispatched though aMES.

The process flow through steps 220, 225 and 230 occurs simultaneouslywith the process flow through steps 235, 240 and 245. There are twoprocess flows because there are specific differences on how schedulingthrough the first operation of a ZOC is handled compared to howscheduling is handled in subsequent operations of the ZOC.

FIG. 5 is a flowchart of step 215 of FIG. 4. In step 250 a ZOC isdefined using data from MES file 200. The ZOC of control is defined bythe product type, first operation in the ZOC, the last operation in theZOC and the maximum amount of time a lot of product this type is allowedto take from completing the first operation of the ZOC to entering thelast operation of the ZOC. A ZOC control is a subset of sequentialoperations of the overall set of operations required to fabricateproduct of the product type.

In step 255, the ZOC is created using data from MES file 200.Information is selected from MES file 200 that will be incorporated inthe file that controls the ZOC. This information includes eachoperation, the tools for each operation, the raw process times for eachtool in the ZOC, the average aggregate raw process time to complete allthe operation in the ZOC and all lot types that need to be run througheach tool of the ZOC. Creating a ZOC is essentially creation of arouting file. In step 260, the ZOC is verified. Essentially, the ZOCrouting file is compared to a subset of the overall routing file, therouting file of MES file 200. If in step 265, the ZOC does not verifythen in step 270, a human operator is notified that a ZOC creation errorhas occurred and the problem may be pointed out. If, in step 265, theZOC does verify then in step 275, the various ZOC CM file are written toZOC CM file 160 and in step 280, ZOC lot tracking file 195 is created.The ZOC tracking file will include ZOC lot target date/time and ZOC lotcomplete estimated date/time data.

FIG. 6 is a flowchart of steps 220 and 225 of FIG. 4. This sequence ofsteps is creating ZOC release date/times for ZOC lots into the first ZOCoperation and estimated complete date/times. In step 290 using the WIPfile of MES file 200, the lot IDs of all lots at the first ZOC operationare determined. In step 295, using the ZOC Lot ID it is determined whichof the lot IDs are ZOC lot IDs and in step 300, the ZOC lot IDs areadded to ZOC tracking file 195 and their information at the first ZOCoperation. In step 305, ZOC lot release date/times are generated andwritten to the ZOC lot release file of ZOC GPRM file 170 and ZOC lotcomplete target date/times are generated and written to ZOC lot trackingfile 195 based on the ZOC lot release date/times and the ZOC requiredcycle time file of ZOC CM file 160. At this point the ZOC lot completetarget date/times are also the ZOC lot complete estimated date/times andthe ZOC lot complete estimated date/times are written to ZOC trackingfile 195. Step 305 is illustrated in FIG. 7 and described in furtherdetail infra. From step 305, the method proceeds to connector A of FIG.9.

FIG. 7 is a flowchart of step 305 of FIG. 6. In step 310, the lot withthe earliest available release date/time into the ZOC tool is selected.In step 315, ZOC lot predicted release and complete date/times for thefirst ZOC operation is generated using the earliest available releasedate/time and the ZOC lot ID file, the non-ZOC lot ID file and the ZOCrequired cycle time file of ZOC CM file 160. Step 315 is illustrated inFIG. 8 and described in further detail infra. In step 320, a ZOCcomplete predicted date/time through all the ZOC operations is generatedusing a simulation model of the ZOC. In a first example, the simulationmodel is a stochastic simulation model (e.g. utilizes probabilities ofprocessing events happening to schedule). In a second example, adeterministic model is used. In a third example, an analytic model isused. In either the first or third examples, the ZOC lot completeestimated date/time may be maximum likelihood point estimated date/timeor range of values with an associated predictive probability densityfunction. In any of the three examples, an additional time may beoptionally added to the nominally calculated ZOC lot complete date/timein order to buffer against cycle time uncertainties. In step 325, theZOC lot complete predicted date/time is compared with the ZOC lotcomplete target date/time from ZOC tracking file 195. If in step 330,this window is not exceeded then in step 335 then the ZOC lot completepredicted date/time will be become the ZOC lot complete estimateddate/time described supra and used in step 305 of FIG. 6. If in step330, this window is exceeded, then in step 340, the ZOC releasedate/time is changed to a later date/time and the process loops back tostep 315.

FIG. 8 is a flowchart of step 315 of FIG. 7 and step 445 of FIG. 11. Instep 345, the designated current ZOC operation is used to initialize thesimulation model. In step 350, using the ZOC lot ID file of ZOC CM file160, all ZOC lots at the current operation are identified. In step 355,using the ZOC lot priority file and the non-ZOC lot priority file of ZOCGPMM file 180 and using the ZOC tool file (having tool logistics data)of ZOC CM file 160 the simulation model is run to generate a ZOC lotcomplete prediction date/time for each lot at the designated ZOCoperation. In step 365 the ZOC lot complete predicted date/time becomesthe ZOC lot complete estimated date/time and is written to ZOC lottracking file 195.

FIG. 9 is a flowchart of step 230 of FIG. 4. This sequence of steps isdeciding the order of ZOC and non-ZOC lots into the first operation ofthe ZOC. In step 380, using the ZOC lot release file from ZOC GPRM file180 and the WIP files from MES file 200, all lots available to run onthe first operation of the ZOC are identified and for ZOC lots therelease date/time resultant from the simulation model is read. In step385, all the lots, ZOC and non ZOC are ranked based lot priorities, toolthroughputs in order to assign a tool and release date/time to theassigned tool based on local release algorithms. For example, if a lothas high priority but its earliest release time is not in the nearfuture, the lot can be assigned a later release date/time that is nolater than the release date/time from the simulation model. In step 390,the tool assignment and release date/time is written to the dispatchlist file of WNM file 190. As steps 380 through 390 are being executed,steps 390 and 400 are also executed. In step 395, the next lot torelease is selected from the dispatch list file of WNM file 190 and instep 400 the MES sends an execute instruction to the floor controlsystem.

FIG. 10 is a flowchart of steps 235 and 240 of FIG. 4. This sequence ofsteps is creating release date/times for ZOC lots into the secondthrough N (or last) ZOC operations. In step 405 using the WIP files ofMES file 200 all the ZOC lots at each ZOC operation from the secondthrough the last are identified. In step 410 ZOC lots identified by theMES as on hold or inhibited are identified (they are flagged in the WIPfiles of MES file 200). A lot may be identified as on hold or inhibitedbecause the lots processing may not continue for some technical processreason (e.g. the lots must be inspected or lot data analyzed prior tothe lot continuing to the next operation).

In step 415, it is determined if any ZOC lot is on hold or inhibited andis in jeopardy of not meeting its ZOC lot complete target date/time bycomparing the ZOC lot's complete estimate to its corresponding ZOC lotcomplete target date/time. For all ZOC lots found to be in jeopardy, analert report is issued in step 420 and written to the ZOC alert file ofZOC GPMM file 180. Alert reports may or may not generate actions by ahuman operator. The method then proceeds to step 425. For all ZOC lotsfound not to be in jeopardy the method immediately proceeds to step 425.In step 425, the estimated ZOC lot complete estimate is written to ZOClot tracking file 195. The operations of step 425 are similar to theoperations performed in FIG. 7 and described supra for the firstoperation of the ZOC, but are modified to account for effects onlyapplicable to second through last ZOC operations. Step 425 isillustrated in FIG. 11 and described in further detail infra. Next, instep 430, it is determined if the recalculated ZOC lot completeestimated date/times for each ZOC lot meets its corresponding ZOC lotcomplete target date/time. If the ZOC lot complete estimated date/timemeets its corresponding ZOC lot complete target date/time then themethod proceeds to connector B of FIG. 13, otherwise the method proceedsto step 435 where a check for recovery actions is performed. Step 435 isillustrated in FIG. 12 and described in further detail infra.

FIG. 11 is a flowchart of step 425 of FIG. 10. In step 440, the lot withthe earliest available release date/time into current operation underanalysis is selected. In step 445, ZOC lot predicted release andcomplete date/times for the current ZOC operation is generated using theearliest available release date/time and the ZOC lot ID file, thenon-ZOC lot ID file and the ZOC required cycle time file of ZOC CM file160. Step 445 is illustrated in FIG. 8 and was described in detailsupra. In step 450, a ZOC complete predicted date/time through all theZOC operations is generated using the simulation model of the ZOC. Instep 455, the ZOC lot complete predicted date/time is compared with theZOC lot complete target date/time from ZOC tracking file 195. If in step460, this window is not exceeded then in step 465 the ZOC lot completepredicted date/time will be become the ZOC lot complete estimateddate/time described supra and used in step 425 of FIG. 10. If in step460, this window is exceeded, then in step 470 it is determined if theZOC lot is at a maximum priority. If the ZOC lot is at a maximumpriority the method proceeds to step 475, otherwise the method proceedsto step 480. In step 475, a check for recovery options is performed.Step 480 is illustrated in FIG. 12 and described in detail infra. Instep 480, the ZOC release date/time is changed to a later date/time andthe process loops back to step 445.

FIG. 12 is a flowchart of steps 435 of FIG. 10 and 480 of FIG. 11. Instep 485, the ZOC lot is placed on the ZOC critical list and recorded inthe ZOC critical list file of ZOC GPMM file 180. In step 490, options torecover are selected based on information in the knowledge base file ofZOC CM file 160 by a human. Any options found are written to the recoveroptions file of ZOC GPMM file 180. In step 495, a critical action reportis issued. Critical actions generally require approval/action by a humanoperator.

FIG. 13 is a flowchart of step 245 of FIG. 4. This sequence of steps isdeciding the order of ZOC and non-ZOC lots into the second through lastoperations of the ZOC. In the following steps, lots at a particular ZOCoperations are processed as a groups, and steps are repeated for eachZOC operation starting from the second ZOC operation. So, in step 500,using the ZOC lot priority file from ZOC GPRM file 170, the WIP filesfrom MES file 200 and the recover options file from ZOC GPMM file 180,all lots available to run on each of the second through last operationsof the ZOC are identified and for ZOC lots the release date/timeresultant from the simulation model is read. In step 505, all the lots,ZOC and non ZOC are ranked based lot priorities, tool throughputs inorder to assign a tool and release date/time to the assigned tool basedon local release algorithms. For example, if a lot has high priority butits earliest release time is not in the near future, the lot can isassigned a later release date/time that is no later than the releasedate/time from the simulation model. Other actions, for example, toolassignment and release to the tool date/time can be changed by a humanoperator in response to information in the recover options file of ZOCGPMM files 180 In step 510, the tool assignment and release date/time iswritten to the dispatch list file of WNM file 190. As steps 500 through510 are being executed, steps 515 and 520 are also executed. In step515, the next lot to release is selected from the dispatch list file ofWNM file 190 and in step 520 the MES sends an execute instruction to thefloor control system.

Generally, the method described herein with respect to a method ofrelease and product flow management is practiced with a general-purposecomputer and the method may be coded as a set of instructions onremovable or hard media for use by the general-purpose computer. FIG. 14is a schematic block diagram of a general-purpose computer forpracticing the present invention. In FIG. 14, computer system 600 has atleast one microprocessor or central processing unit (CPU) 605. CPU 605is interconnected via a system bus 610 to a random access memory (RAM)615, a read-only memory (ROM) 620, an input/output (I/O) adapter 625 fora connecting a removable data and/or program storage device 630 and amass data and/or program storage device 635, a human interface adapter640 for connecting a keyboard 645 and a mouse 650, a port adapter 655for connecting a data port 660 and a display adapter 665 for connectinga display device 670.

ROM 620 contains the basic operating system for computer system 600. Theoperating system may alternatively reside in RAM 615 or elsewhere as isknown in the art. Examples of removable data and/or program storagedevice 630 include magnetic media such as floppy drives and tape drivesand optical media such as CD ROM drives. Examples of mass data and/orprogram storage device 635 include hard disk drives and non-volatilememory such as flash memory. In addition to keyboard 645 and mouse 650,other human input devices such as trackballs, writing tablets, pressurepads, microphones, light pens and position-sensing screen displays maybe connected to human interface 640. Examples of display devices includecathode-ray tubes (CRT) and liquid crystal displays (LCD).

A computer program with an appropriate application interface may becreated by one of skill in the art and stored on the system or a dataand/or program storage device to simplify the practicing of thisinvention. In operation, information for or the computer program createdto run the present invention is loaded on the appropriate removable dataand/or program storage device 630, fed through data port 660 or typed inusing keyboard 645.

Thus the present invention provides a method of release and product flowmanagement for a manufacturing facility that allows for improved yieldas well as cycle time and delivery schedule control.

The description of the embodiments of the present invention is givenabove for the understanding of the present invention. It will beunderstood that the invention is not limited to the particularembodiments described herein, but is capable of various modifications,rearrangements and substitutions as will now become apparent to thoseskilled in the art without departing from the scope of the invention.Therefore, it is intended that the following claims cover all suchmodifications and changes as fall within the true spirit and scope ofthe invention.

1. A method for scheduling lots of product through operations in amanufacturing line, comprising: selecting a sequential subset of a setof sequential operations required to manufacture said lots; partitioningsaid lots of product into designated lots and non-designated lots;generating a release schedule for each of said non-designated lots intoone or more operations of said sequential subset of said set ofsequential operations; and generating a release schedule for each ofsaid designated lots into each operation of said sequential subset ofsaid set of sequential operations such that for each designated lot atotal amount of time measured from completion of a first operation ofsaid sequential subset of said set of sequential operations throughstart of a last operation of sequential subset of said set of sequentialoperations does not exceed a target amount of time for said designatedlots.
 2. The method of claim 1, further including: generating a releaseschedule for each lot of said designated lots into said first operationof said sequential subset of said set of sequential operations based onall existing release schedules of said designated and saidnon-designated lots into all operation of said sequential subset of saidset of sequential operations.
 3. The method of claim 2, furtherincluding: modifying existing release schedules of said non-designatedlots into said first operation of said sequential subset of said set ofsequential operations based on all existing release schedules of saiddesignated and said non-designated lots into all operations of saidsequential subset of said set of sequential operations.
 4. The method ofclaim 2, wherein said release schedule of each lot of said designatedlots into said first operation of said sequential subset of said set ofsequential operations is generated using a simulation model of saidsequential subset of said set of sequential operations.
 5. The method ofclaim 1, further including: generating a release schedule for each lotof said designated lots into second through last operations of saidsequential subset of said set of sequential operations based onscheduling priorities of said designated and said non-designated lotsinto all operations of said sequential subset of said set of sequentialoperations and based on all existing release schedules of saiddesignated and said non-designated lots into all operations of saidsequential subset of said set of sequential operations.
 6. The method ofclaim 5, further including: modifying existing release schedules of saidnon-designated lots into said second through last operations of saidsequential subset of said set of sequential operations based on allexisting release schedules of said designated and said non-designatedlots into all operations of said sequential subset of said set ofsequential operations.
 7. The method of claim 5, wherein said generatinga release schedule for each lot of said designated lots into secondthrough last operations of said sequential subset of said set ofsequential operations modifies existing release schedules of saiddesignated lots into said second through last operations of saidsequential subset of said set of sequential operations based on allexisting release schedules of said designated and said non-designatedlots into all operations of said sequential subset of said set ofsequential operations.
 8. The method of claim 5, wherein said releaseschedule of each lot of said designated lots into said second throughlast operations of said sequential subset of said set of sequentialoperations is generated using a simulation model of said sequentialsubset of said set of sequential operations.
 9. The method of claim 1,further including: releasing said non-designated lots into operations ofsaid sequential subset of said set of sequential operations according tosaid release schedule for each of said non-designated lots; andreleasing said designated lots into operations of said sequential subsetof said set of sequential operations according to said release schedulefor each of said designated lots.
 10. A computer program product,comprising a computer usable medium having a computer readable programcode embodied therein, said computer readable program code comprising analgorithm adapted to implement a method for scheduling lots of productthrough operations in a manufacturing line, said method comprising thesteps of: selecting a sequential subset of a set of sequentialoperations required to manufacture said lots; partitioning said lots ofproduct into designated lots and non-designated lots; generating arelease schedule for each of said non-designated lots into one or moreoperations of said sequential subset of said set of sequentialoperations; and generating a release schedule for each of saiddesignated lots into each operation of said sequential subset of saidset of sequential operations such that for each designated lot a totalamount of time measured from completion of a first operation of saidsequential subset of said set of sequential operations through start ofa last operation of said sequential subset of said set of sequentialoperations does not exceed a target amount of time for said designatedlots.
 11. The computer program product of claim 10, further includingthe method step of: generating a release schedule for each lot of saiddesignated lots into said first operation of said sequential subset ofsaid set of sequential operations based on all existing releaseschedules of said designated and said non-designated lots into alloperations of said sequential subset of said set of sequentialoperations.
 12. The computer program product of claim 11, furtherincluding the method step of: modifying existing release schedules ofsaid non-designated lots into said first operation of said sequentialsubset of said set of sequential operations based on all existingrelease schedules of said designated and said non-designated lots intoall operations of said sequential subset of said set of sequentialoperations.
 13. The computer program product of claim 11, wherein saidrelease schedule of each lot of said designated lots into said firstoperation of said sequential subset of said set of sequential operationsis generated using a simulation model of said sequential subset of saidset of sequential operations.
 14. The computer program product of claim10, further including the method step of: generating a release schedulefor each lot of said designated lots into second through last operationsof said sequential subset of said set of sequential operations based onscheduling priorities of said designated and said non-designated lotsinto all operations of said sequential subset of said set of sequentialoperations and based on all existing release schedules of saiddesignated and said non-designated lots into all operations of saidsequential subset of said set of sequential operations.
 15. The computerprogram product of claim 14, further including the method step of:modifying existing release schedules of said non-designated lots intosaid second through last operations of said sequential subset of saidset of sequential operations based on all existing release schedules ofsaid designated and said non-designated lots into all operations of saidsequential subset of said set of sequential operations.
 16. The computerprogram product of claim 14, wherein the method step of generating arelease schedule for each lot of said designated lots into secondthrough last operations of said sequential subset of said set ofsequential operations modifies existing release schedules of saiddesignated lots into said second through last operations of saidsequential subset of said set of sequential operations based on allexisting release schedules of said designated and non-designated lotsinto all operations of said sequential subset of said set of sequentialoperations.
 17. The computer program product of claim 14, wherein saidrelease schedule of each lot of said designated lots into said secondthrough last operations of said sequential subset of said set ofsequential operations is generated using a simulation model of saidsequential subset of said set of sequential operations.
 18. The computerprogram product of claim 10, further including the method step of:releasing said non-designated lots into operations of said sequentialsubset of said set of sequential operations according to said releaseschedule for each of said non-designated lots; and releasing saiddesignated lots into operations of said sequential subset of said set ofsequential operations according to said release schedule for each ofsaid designated lots.
 19. A system for scheduling lots of productthrough operations in a manufacturing line, comprising: a zone ofcontrol creation module for initializing a zone of control database fora zone of control of a manufacturing line, said zone of controlcomprising a sequential subset of a set of sequential operationsrequired to manufacture said lots, said lots of product partitioned intodesignated and non-designated lots; a zone of control release module forplanning a release schedule for said designated lots of said lots intoeach operation of said zone of control to meet a total amount of timetarget, said total amount of time target measured from completion of afirst operation of said zone of control through start of a lastoperation of zone of control; a zone of control monitor module forupdating said release schedule of said designated lots and releaseschedules of said non-designated lots into each operation of said zoneof control; and a what next module for selecting a next lot from saiddesignated and said non-designated lots to release into each operationof said zone of control.
 20. The system of claim 19, further including:means for linking said zone of control creation module, said zone ofcontrol release module, said zone of control monitor module and saidwhat next module to a manufacturing execution system; and means forlinking said zone of control database to a manufacturing executionsystem database of said manufacturing execution system.